Performance, combustion and emission parameters of Scenedesmus obliquus methyl ester in single-cylinder CI engine: an experimental study

The growing interest in third-generation microalgae-derived biofuels is driven by their high oil content and rapid growth rate, making them a promising alternative fuel source. This experimental investigation examines the performance, combustion and exhaust emissions of a single-cylinder 5.2 kW CI engine using Scenedesmus obliquus microalgae neat oil and biodiesel. Analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, UV–visible spectrometry, GC–MS and elemental analysis were employed to characterize the Scenedesmus obliquus methyl ester. The brake thermal efficiency (BTE) of Scenedesmus obliquus methyl ester (SOME) is 31.03% which is closer to that of diesel at 32.73%, whereas neat algae oil is 29.26%, which is lower than that of both diesel and SOME at full load. Biodiesel and neat algae oil exhibit significantly lower combustion characteristics, such as combustion duration, in-cylinder pressure and heat release rate (HRR) and ignition delay period under maximum load conditions compared to diesel. Emissions parameters of unburned hydrocarbons (UBHC), carbon monoxide (CO) and smoke emission are higher than diesel. Notably, biodiesel produces higher nitrogen oxide (NOx) emissions than both diesel and neat algae oil. These findings provide valuable insights into the potential benefits and challenges of integrating these biofuels into conventional engine applications.